The present invention relates, in general, to a truck-mounted brake assembly, and more particularly, to an overload protection device for a truck-mounted brake assembly on a railcar.
Prior to the present invention, the brakes on a truck-mounted brake assembly operate through the brake rigging either pneumatically, in response to the supply and release of compressed air at a brake cylinder device, or manually, in response to the operation of the railway car handbrake wheel. As illustrated in FIG. 3, the assembly consists of truss-type brake beams, with one beam having an expansible brake actuator in the form of a brake cylinder mounted thereon. The brake rigging operates in response to the supply and release of compressed air from the brake cylinder. Having its fixed end secured to the left-hand side of the compression member of the brake beam, the brake cylinder responds to the supply of compressed air by an axial expansion of its free end relative to its fixed end. Being connected to an equalizing lever by a force transmitting member, the free end of the brake cylinder effects rotation of the equalizing lever about a pivot pin in a counterclockwise direction, as the brake cylinder expands axially with the supply of compressed air. This counterclockwise rotation of the equalizing lever results in the force-transmitting member being moved in the direction of the right hand, to effect counterclockwise rotation of the equalizing lever about its pivot pin. A portion of the force-transmitting member is secured to the fixed end of the brake cylinder, where resistance to movement is encountered at the end of the equalizing lever connected to the force-transmitting member by the pin, so that this lever acts as a second-class lever. The force exerted at the other end of the equalizing lever from the force-transmitting member causes the equalizing lever to pivot about its connection with the force-transmitting member and thereby move the brake beam in the direction of the right hand through the connection of the equalizing lever with the strut bar, thereby bringing the brake shoes of the brake head and brake shoe assemblies associated with the brake beam into engagement with the wheel treads of the wheel/axle unit. Once this brake shoe engagement occurs, the connection of equalizing lever with the force-transmitting member becomes solid, and the equalizing lever becomes a second-class lever. Thus, the continued expansion of the free end of the brake cylinder causes a counterclockwise rotation of the equalizing lever to take place by pivotal rotation about the pin connection of the equalizing lever with the force-transmitting member. Accordingly, the force of expansion of the brake cylinder acts through the pin of the equalizing lever and the strut bar to force the brake beam in the direction of the left-hand, thereby bringing the brake shoes of the brake head and the brake shoe assemblies associated with the other brake beam into engagement with the wheel treads of the second wheel/axle unit.
An example of this type of truck-mounted brake assembly is taught in U.S. Pat. No. 4,613,016. The teachings of this reference are incorporated herein by reference thereto.
Similarly, rotation of the end of the actuating lever in a counterclockwise rotation, when the handbrake chain is taken up in a well-known manner, affects the same result. An example of this type of truck-mounted brake assembly is taught in U.S. Pat. No. 5,069,312. The teachings of this reference are incorporated herein by reference thereto.
A common practice in the railway industry is to activate the pneumatic, and then the manual brake systems on a single railcar as a precaution against unwanted or unexpected movement of the car. This multiplies the forces on the brake assembly; therefore the brake beams may be subjected to a force exceeding their ultimate load capacity, thus causing deflection and premature failure. The present invention is designed with a preloaded compression member to absorb the excess force before deflection and possible failure of the brake beam occurs.
In a first aspect, the present invention provides an overload protection device for a truck-mounted brake assembly comprising a body member having a first end, a second end, at least one cavity of a predetermined size and shape disposed within the body member, and a compression member of a predetermined size, shape, material, and load rating, having a primary end and a secondary end. The compression member is compressed to a predetermined initial load, and is disposed within the cavity of the body member. The present invention further comprises a first means secured to and disposed on the first end of the body member for engagement with a portion of a brake assembly, and a second means disposed on the second end of the body member for attaching to a force-transmitting member. A first portion of the second means is engageable with the compression member for transmitting an excess force generated from a railcar brake assembly to the compression member, whereby the overload protection device will compensate for a potential railcar brake overload condition.
In a further aspect, the present invention provides an overload protection device for a truck-mounted brake assembly comprising a body member having a first end, a second end, at least one cavity of a predetermined size and shape disposed within the body member, and a compression member of a predetermined size, shape, material, and load rating. The compression member is compressed to a predetermined initial load, and is disposed within the cavity of the body member. A flange of a predetermined size and shape has a first surface and a second surface. The first surface is disposed on the second end of the body member. A first means is secured to and disposed on the first end of the body member for engagement with a portion of the brake assembly. A second means is reciprocally mounted adjacent to the second end of the body member for attaching to a force-transmitting member. A first portion of the second means is engageable with the compression member for transmitting an excess force generated from a railcar brake assembly to the compression member. A retaining element is secured to and disposed on the second surface of the flange. The retaining element has an aperture of a predetermined size and shape concentrically disposed therein, wherein a second portion of the second means is reciprocally disposed therein. The overload protection device will compensate for a potential railcar brake overload condition.
In still a further aspect, the present invention provides an overload protection device for a truck-mounted brake assembly comprising a body member having a first end, a second end, and at least one cavity of a predetermined size and shape disposed within the body member. A compression member of a predetermined size, shape, material, and load rating has a primary end, a secondary end, and a concentric bore of a predetermined size and shape disposed from the primary end to the secondary end. The compression member is disposed within the cavity of the body member. A first means is secured to and disposed on the first end of the body member for engaging a portion of the brake assembly. A second means is disposed within the concentric bore of the compression member, and is engageable with the compression member and connectable to a force-transmitting member. A securement member is disposed on the second end of the body member for securing the compression member in the cavity of the body member, whereby the overload protection device will compensate for a potential railcar brake overload condition.
In addition to the various objects of the invention that have been described above, various other objects and advantages of the invention will become more readily apparent to those persons skilled in the relevant art from the following more detailed description of the invention, particularly, when such description is taken in conjunction with the attached drawing figures and the appended claims.
It is therefore a primary object of the present invention to provide a device to protect brake overload in a truck-mounted brake assembly on a railcar.
Another object of the present invention is to provide a device to protect brake overload in a truck-mounted brake assembly on a railcar by compensating for multiple forces that may exceed the ultimate load capacity of the brake beams.
Still a further object of the present invention is to provide a device to protect brake overload in a truck-mounted brake assembly on a railcar by absorbing the excess force before deflection and possible brake beam failure occurs.
In addition to the various objects of the invention that have been described above, various other objects and advantages of the invention will become more readily apparent to those persons skilled in the relevant art from the following more detailed description of the invention, particularly, when such description is taken in conjunction with the attached drawing figures and the appended claims.